The present invention relates to apparatus for providing a manifestation of the depth relationships in a three-dimensional scene and, more particularly, to such an apparatus which makes depth perception television a practical reality.
Much effort by many investigators has been devoted to producing three-dimensional television. The most effective visual cue for perceiving depth is achieved by presenting to each of the observer's retinas a separate view of the same scene as seen from two points which are separated laterally by an amount comparable to the binocular viewing base. This can be achieved in numerous ways and many variants have been proposed. The simplest way, in theory, is to use two conventional television cameras to record the differing views and then transmit such views along two separate channels for observance on two separate television receivers. The images on the two television monitors are then directed separately to the viewer's eye for which each is intended, by mirrors, prisms, special filters or related optical devices so that the differential parallax between the views provides the observer with an adequate "depth cue". While this approach is simple in concept, there are several difficulties which have precluded it from being commercially significant. For one, the transmission bandwidth needed for each presentation is doubled in view of the necessity of separately transmitting the two disparate images of the scene. Moreover, it has been found that the problem of assuring that each of the images is only transmitted to the eye of the viewer for which it is intended is not simple. While numerous ingenious proposals for solving this problem have been suggested, they have generally been more complex or expensive than is acceptable. For instance, the stereopair of views may be transmitted by a single camera by alternately transmitting the right eye and left eye view at a frequency greater than the flicker rate, or dividing the input face of the camera tube so that both the right and left eye images share one-half the input window simultaneously. A similar arrangement is contrived at the display terminal by alternately shielding the right and left eyes synchronously with the alternation at the transmitter, or by shielding the right and left eye views from the opposite eye when a split display screen is being used. These proposals have required more extensive changes to present video technology and equipment than manufacturers and consumers have been willing to adopt.